screen sharing computer sound

With screen sharing, computer sound, I loop the music straight to the participants. The camera transmits dance movements that go with the music. That has worked well so far. Yesterday, however, my recording and also the feedback from my participants showed that the music was delayed for 1 hour. I.e. it came too late, later than the dance movement. The dance no longer fit the music. At the beginning it was only true, over the course of 60 minutes it was increasingly delayed. almost half a bar. What can be the reason?